This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Multiple NHP (nonhuman primate) species, including 5 species of macaques and 3 species of langurs, coexist with humans in different areas and ecological contexts in Bangladesh, one of the most densely populated countries in the world. Interaction among populations of NHPs as well as between humans and NHPs increases the likelihood of cross-species transmission of infectious agents. Our 5 year R01 project in Bangladesh is characterizing the epizootiology and evolution of two enzootic simian retroviruses, simian foamy virus (SFV) and simian type D retrovirus (SRV) in macaques and langurs where they occur in a variety of geographic areas and contexts throughout Bangladesh. The initial proposal identified 20 sites that have varying degrees of contact between humans and NHPs, diverse ecological conditions and from 1 to 6 species of NHPs present. Phylogenetic and phylodynamic analyses will elucidate how these viruses have changed over time through co-evolution with their hosts, recombination and host switches. These studies will be complemented by studies on the demographic histories of non-human primate populations. We are also measuring the prevalence of SFV and SRV infection in human populations. We are starting the second year of our project. We have started to assemble a cohort of SFV positive humans in Bangladesh. 14/177 humans that we have sampled to date are seropositive for SFV, the highest seroprevalence of this simian-borne retrovirus in any human population studied to date. We have identified individuals co-infected with SFV and SRV. We have also identified individuals infected with more than one strain of SFV. Genetic analysis has revealed that the SRV detected in the free-ranging NHPs in Bangladesh is not any of the known simian type D retroviruses 1-5. Further research will elucidate the diversity of SRV in NHP populations in Bangladesh, and may demonstrate new, heretofore undescribed retroviruses.